Abstract As for the karst area overlying soft plastic red clays, artificial dewatering and construction disturbance will cause collapse of karst ground and endanger tunnel construction and operation safety. The collapsing mechanism of the soft plastic red clay overlying karst area and the construction risks of shield tunnel in soft plastic red clay and the hard plastic red clay soil layer are analyzed, and the corresponding measures are established. The results show that dewatering destroys the equilibrium state among soil, fissure water and karst cave, leads to flowing of red clay into karst cave and the tunnel will subside with the subsidence of soft plastic red clay if the tunnel is located in soft plastic red clay stratum; after flowing of soft plastic red clay into karst cave, the soft plastic red clay layer collapses and a soil cave is formed between the plastic red clay layer and the hard plastic red clay layer and eventually the tunnel subsides due to low shear strength and cohesion, if the tunnel is located in hard plastic red clay layer; if the inclination of limestone surface is large and this will extend the settlement range of red clay. The following measures like filling of karst cave within the scope of high risks, reinforcement of the soft plastic red clay layer and adding of anti-sliding piles at the place with large inclination are adopted to manage the above mentioned risks.
Abstract：
As for the karst area overlying soft plastic red clays, artificial dewatering and construction disturbance will cause collapse of karst ground and endanger tunnel construction and operation safety. The collapsing mechanism of the soft plastic red clay overlying karst area and the construction risks of shield tunnel in soft plastic red clay and the hard plastic red clay soil layer are analyzed, and the corresponding measures are established. The results show that dewatering destroys the equilibrium state among soil, fissure water and karst cave, leads to flowing of red clay into karst cave and the tunnel will subside with the subsidence of soft plastic red clay if the tunnel is located in soft plastic red clay stratum; after flowing of soft plastic red clay into karst cave, the soft plastic red clay layer collapses and a soil cave is formed between the plastic red clay layer and the hard plastic red clay layer and eventually the tunnel subsides due to low shear strength and cohesion, if the tunnel is located in hard plastic red clay layer; if the inclination of limestone surface is large and this will extend the settlement range of red clay. The following measures like filling of karst cave within the scope of high risks, reinforcement of the soft plastic red clay layer and adding of anti-sliding piles at the place with large inclination are adopted to manage the above mentioned risks.
ZHUO Xuyang
.Countermeasures for the Shield Tunnel Passing through the Karst Area Overlying Soft Plastic Red Clays[J] MODERN TUNNELLING TECHNOLOGY, 2019,V56(6): 196-202
2019, Vol. 56 